Within, for example, base stations for mobile telephony, there is often a requirement to be able to control the various subsystems in the base station rapidly and flexibly in real time, which places great demands on the amounts of data that have to be transmitted from a control unit in the base station to the various subsystems. These great demands on the transmission of data in real time occur, in principle, in all the subsystems in the base station, but will be illustrated below based on the need that arises if a base station utilizes so-called active electrically controlled antennas.
An active electrically controlled antenna usually comprises a large number of so-called transmitter/receiver modules, where, in principle, each module is a separate antenna that is controlled individually with regard to amplification and phase, so that the required antenna pattern for the whole of the electrically controlled antenna is obtained. The control is usually carried out by each module receiving information from an external control unit concerning the direction that the main lobe of the antenna should have, after which a calculation is carried out in the module concerning the settings, for example phase, that the module is to have in order to give the required direction.
In future systems, the requirement to be able to use antennas for additional functions will increase. This is particularly evident within telecommunication applications, such as base stations for mobile telephony, where the requirement can be foreseen that, in addition to traditional transmission and reception, the antennas will have to be able to be used for other applications, for example for finding the direction of sources of interference in order to be able subsequently to neutralize the effects of these. Another function for which there could possibly be an increased requirement in the future is the ability to concentrate the transmission to certain areas by shaping the antenna pattern in a particular way, by using so-called lobe shaping.
One of the difficulties in achieving a system with the characteristics of flexibility and rapid combination of different functions can be illustrated by the following calculation: An electrically controlled antenna with 1000 transmitter/receiver modules is to be controlled in such a way that it changes the direction of its main lobe in a microsecond. If 6 bits are needed for the phase setting of each module, the transmission speed that is required will be 1000*6*1000000=6 Gbit/second, which is a transmission speed that is so high that it will be expensive and difficult to implement. Additional functionality of the transmitter/receiver modules, and a rapid and flexible use of these, would demand even higher transmission speeds, and thereby result in even higher costs.
Regarding active electrically controlled antennas in an application other than mobile telephony, namely radar systems, there could be requirements that, in addition to handling traditional radar functions, the antenna should also be able to be used for listening, communication and interference functions. In order to make possible an effective utilization of the radar equipment, a rapid combination of these different functions must be possible, which can be extremely complex, as each of the different functions has itself a high degree of complexity. An additional requirement concerning the control of a system with a plurality of different functions is that it should be flexible, in order to enable it to have the potential for development and modification based on future user requirements.
U.S. Pat. No. 5,917,447 describes an electrically controlled antenna according to known technology, which requires a special calculation algorithm on account of the complexity of the control of the device.